1. Field of the Invention
The present general inventive concept relates to a semiconductor memory, and more particularly, to a write driver circuit of a semiconductor memory having an unmuxed bit line scheme.
2. Description of the Related Art
In general, a memory supporting wide Bit Per Word (BPW) has a fat structure. In particular, in case of a register file memory mainly used for replacing a register array of a System On Chip (SOC), the area of the register file memory tends to be fat during designing of a chip. It is important to reduce the height of a memory, instead of the width, in a fat-type memory for reducing the area of a chip in a memory.
Meanwhile, a memory supporting wide BPW requires an unmixed bit line structure and an unmixed Y-path (also referred to as “unmuxed”). Here, the unmuxed Y-path refers to a path including circuits relating to output paths (that is, a sense amplifier, an output latch, and an output buffer) and circuits relating to input paths (that is an input buffer, an input latch, and a write driver) in each column.
That is, the unmuxed Y-path maximizes bandwidth for reading out/writing data existing in a number of bit lines at the same time, instead of for selectively reading out/writing data existing in the bit lines selected from among a number of bit lines through a multiplexer (MUX). Accordingly, if n (n is a natural number) columns exist, n Y-paths are needed.
However, as mentioned above, such an unmuxed Y-path should include all circuits relating to output paths (that is, a sense amplifier, an output latch, and an output buffer) and circuits relating to input paths (that is an input buffer, an input latch, and a write driver) in each column so that a height of the unmuxed Y-path is much higher than that of a control circuit block during designing of a chip. In particular, in the unmuxed Y-path, the write driver occupies a significantly large space. Thus, in order to reduce the area of a chip in the memory having the unmuxed Y-path, that is, an unmuxed bit line scheme, so as to reduce a cost of the memory, it is important to simplify the structure of the write driver circuit and thus reduce the area occupied by the write driver circuit, thereby reducing the height of the unmuxed Y-path.